Objective To establish a stable colorectal cancer model in liver specific insulin-like growth factor (IGF)-1 deficient (LID) mice and examine the potential relationship between IGF-1 level and risk of mice constitutional colorectal cancer. Methods ①Establishment of a colorectal cancer model: The LID mice, in which IGF-1 level in circulation was 25% of BALB/c mice. Induction of colorectal cancer was achieved by using the 1,1 Dimethylhydrazine (DMH) with hypodermic injection at transverse part. ②Eighty fresh samples of cancer tissues and adjacent tissues were obtained from LID mice (experimental group) and BALB/c mice (control group). The expression of IGF-1 was studied by immunohistochemical assay (SP method). Results ①Weight loss occurred in both experimental group and control group after injection. Compared with the body weight before injection on 18 weeks and 24 weeks in each group, there were significant differences after injection at the same phase in each group (P＜0.05). ②The results of IGF-1 expression in cancer tissues and adjacent tissues: IGF-1 got a diffuse distribution in cancer cell cytoplasm. The positive expressions of IGF-1 in the cancer tissues and their adjacent cancer tissues were 6/7, 2/7 and 13/16, 7/16 respectively in experimental group and control group. There were significant differences between the cancer tissues and adjacent tissues inside both groups (P＜0.05). There were no significant differences inside both of cancer tissues and adjacent tissues respectively between experimental group and control group (Pgt;0.05). Conclusion In the established colorectal cancer model by DMH, IGF-1 plays an important role in the development and progression of colorectal cancer.
